Other people only know you either directly from the interactions they have with you, or indirectly by third parties who claim to have had interactions with you. In this light, the term SerialIdentity means something more like "serial interactions". However, since we have interactions all day long with numerous people, that doesn't make for much of a singular distinct identity. Instead, a SerialIdentity is some subset of these interactions that can be connected together as (likely) belonging to a unique individual. For example, on a MailingList, all the e-mails from "Alice" are assumed by the other list members as belonging to some unique individual named "Alice" (not necessarily her RealName). Another example, in the news you often hear about the President of the United States, so you assume there is one person to whom you could prescribe all those distinct, disjoint, and discrete news reports, even if you haven't met that individual yourself.
Really what that describes is reputation. The terms serial identity and reputation seem equivalent. However, generally we consider the SerialIdentity to be the name (nym) associated with the set of data that constitutes the reputation. To some, the nym is redundant with the data, so they may reduce the two terms to mean the same thing, although that isn't necessarily a useful idea. Most people have an attachment to their names.
Since reputation amounts to data, a quantifiable reputation can be computed algorithmically for a certain end. This is particularly useful in certain situations online where the substantive quality of an identity is irrelevant, and only its functional role matters. An EbayDotCom auctioneer's reputation is a simple rating based on functionality for delivering on her sales, not on what she is selling and why. Similarly, a website's user's click trajectory is a SerialIdentity based on her "reputation" for the URLs she requested, but that identity is devoid of any depth--no motivations, no purpose, no reactions. Note in the latter case how irrelevant the user's actual name is, or even that the user has a name separated from her click trajectory.
Conversely, for OnlineCommunities (or any community), SerialIdentity provides a much more meaningful role by ascribing depth to each participant. By constructing a SerialIdentity, each member can get to know one another, form teams and relationships, communicate with others over time, build trust (partly by being accountable), and otherwise socialize with the others. This is a much deeper type of identity than the simply numeric one mentioned just above, and consequently it provides for larger social gains and therefore larger overall functional gains. It shouldn't be held that SerialIdentity is necessary to build a communal work, however, as certainly anonymous (i.e. disjoint, discrete, distinctive) interactions can lead to EmergentBehaviour? through IncidentalCollaboration (compare AnonymousWiki); what is true is that SerialIdentity is necessary to build a community. (cf. WhatIsaCommunity) From that, it should also be clear that when someone takes the time and trust to build a SerialIdentity--that is, to introduce themselves--they are putting in an emotional stake into the community. This is why it is important to RewardReputation.
Methods of creating SerialIdentity are numerous. You can directly create a SerialIdentity by announcing your name. Usually this means your RealName (a la UseRealNames), although a consistent PenName such as Mark Twain would work as well, or even a number assigned automatically by some system like your passport number. You can indirectly create a SerialIdentity from information you project that could only come from you, such as your visual appearance or your voice. For instance, the butcher you go to once a week will recognize you on sight. Similarly, your IP address or domain may also identify you uniquely (e.g. on our RecentChanges) given a small enough context; more generally, the NetworkDistance between the series of your transactions can help identify you.
Either method is open to ambiguity. RealNames are non-unique in most cases. A PenName may be used by several people. One group could employ a PenName consistently and uniquely to represent them collectively. Alternatively, several unaffiliated individuals may co-opt that PenName for their own distinct purposes. Similarly, indirect means are open to ambiguity. Your butcher may mistake your identitical twin for you, and IP addresses aren't a very solid one-to-one match for individuals.
One point remains, however. Ignoring PostModernism (cf. WhatIsMultiplicity), there still is one identity underlying each of these interactions. Identities have a tendency to not change sharply from moment to moment. The uniqueness and distinctness of each person is reflected in each interaction by the choices and style and substance involved. For instance, what you write, where you write, when you write, and how you write all reflect the essence of who you are. It's well known that writing styles are hard to mimic and harder to change. Personalities are even harder. No matter what, your collection of serial identities all represent one singular identity. This uniqueness can often be sufficient to construct a serial identity. That is, you can tie a person's contributions together by their style alone. While this is the most indirect method to construct a serial identity, making it subject to the most doubt, it is powerful. Moreover, people are hardwired to find these patterns automatically. This can be a powerful defense against IdentityTheft as well as the community will serve as "character witnesses" on your behalf. It is also a strong point to remember before considering other computer-based reputation schemes for your OnlineCommunity. Perhaps a simple CommunitySolution is all you need.
Moved from RewardReputation. Should be folded with the above...
Creating a community requires members to form relationships with each other. While in the RealWorld this is natural, mediated communication suffers from certain drawbacks, including discontinuity. TransactionBasedCommunity is particularly discontinuous. Relationships deeper than single interactions build from the continuity of SerialIdentity. Although we don't (normally) suffer from the inability to connect events to people in offline relationships, the online situation demands effort to overcome the initial architectural limitations. The most common solution is to attach a nym to each person's actions, such as through logins, UserNames, IPs/domains, or visual representations (avatars).
Even without a nym, though, all methods amount to collecting the set of each member's actions--a reputation. While in daily life, we typically keep track of our acquaintances in our memories or through indirect record keeping, online communication allows for tracking at a whole new level. Since every transaction goes through software, every transaction can be tracked and logged perfectly. Of course, just because there is a lot of data available doesn't mean anyone is going to spend the time to use it. Therefore, a person's reputation is both what is logged and what is remembered.
A person may create a reputation without any concern for the reactions of the larger community, such as when some random individual decides to create a Wiki:WalledGarden on someone else's wiki, or more commonly when IncidentalCollaboration is logged for public view. In the case of a community, though, people generally do not spend the effort in building a reputation unless they are seeking to connect with the rest of the community. This means that reputations are strongly connected to emotional stakes; the more effort one puts in building a strong reputation, the more emotionally invested one is.
Of course, reputations aren't limited to one community. Within the GlobalVillage, individuals play many roles, interconnected or discrete or even discreet. People create a SerialIdentity as they move from place to place. Often people will voluntarily identify themselves, usually with their RealName, although online it's common practice to employ a PenName. Using a PenName online has its advantages if you consider that too many things are recorded that you'd sooner ForgiveAndForget. Reputation has its ugly side. Also, many people believe in extreme forms multiplicity (cf. WhatIsMultiplicity) that allow for such things as IdentityTourism?.
In order to help connect an identity across such diverse spaces in a consistent, definite way, many people have worked on cryptographically secure reputation systems. They either rely on a TrustedThirdParty? that assigns a unique number to each individual or a WebOfTrust that assigns a unique node in a network to each individual. As these schemes do not rely on society, they do not create a sense of emotionalism, which might be a good thing. On the other hand, they shouldn't be considered a valuable tool for assessing character, just merely as a method for assigning quantifiable facts to one nym. Thus, a WebOfTrust doesn't really indicate trustworthiness of a person, just that a given nym is associated with a given node to some degree of probability.
Joining a community means forming a relationship with TheCollective, which means getting to know one another. This naturally implies creating a SerialIdentity. In normal RealWorld relationships, this is the natural course of things. Your friends ought to recognize you when they see you unless you do something complicated to confuse them. In mediated relationships, as with OnlineCommunities, the natural course is near anonymity. Unless your style shines through to identify you, or time structures a temporary anonymous encounter such as random chat, you are as distinct as white paint.
Most online communities have architecturally created SerialIdentity. Many communities require that their members create user accounts that log all their actions on the site. The members are typically barred from entering (much of) the community until they identify themselves to the logging system, hence the term "log in." Other viable systems request or require users to identify themselves for each interaction. A mailing list, for example, serially identifies members from the From: fields in the message headers. Wikis are another important example, as all wiki interaction is through freeform text, logins don't do anything. Instead, authors use signatures, and optionally UserNames for RecentChanges.
That's not been true in my experience.... it seems more frequently the case that those newly interacting with multiplicity folks feel that multiples shouldn't be held responsible for the actions of their SockPuppets, whereas the multiplicity folks know that they should be and they have to be. Certainly any kind of multiplicity site is likely to contain essays on the subject arguing for collective responsibility. MartinHarper